1. Slide design: Dr. Mark L. Hornick
SE3910
4/12/2019
SE3910 Week 2, Class 3
Today
Nervous System Response Time
Includes material by Dr. Larry Fennigkoh
In Lab: Quiz
More circuits
Definition of Real Time System
Microcontroller vs. Microprocessor
Latency terminology
Response time computation
SE-2811
Slide design: Dr. Mark L. Hornick
Content: Dr. Hornick
Errors: Dr. Yoder
Dr. Josiah Yoder

2. Measure your class-mate’s response time
4/12/2019
Measure your class-mate’s response time
SE3910 Week 3, Class 2
SE Dr. Josiah Yoder
Slide style: Dr. Hornick
Much Material: Dr. Schilling
Dr. Josiah Yoder

3. Instructions Part 1 Part 2 Partners swap roles…
SE3910
4/12/2019
Instructions
Part 1
One partner should hold the stick while the other partner places their hand around the tape at the end of the stick. Hands should be approximately 1” from the stick.
At some point in the future, the partner drops the stick. Read the numbers off of the stick for response time and record them in the GoogleDoc.
Repeat the experiment 3 times
Part 2
One partner should hold the stick while the other partner places their hands around the tape at the end of the stick. Hands should be approximately shoulder width apart.
Partners swap roles…
SE Dr. Josiah Yoder
Slide style: Dr. Hornick
Much Material: Dr. Schilling
Dr. Josiah Yoder

4. Human Systems Sensory: Inputs: Both external & internal
CS2852
4/12/2019
Human Systems
Sensory:
Inputs: Both external & internal
Outputs: Nerve signals
Nervous:
Inputs: Nerve signals
Outputs: Intelligent nerve signals
Motor:
Outputs: Precise & powerful motion
SE Dr. Josiah Yoder
Slide style: Dr. Hornick
Much Material: Dr. Schilling
Dr. Yoder

5. Human Nervous System SE3910 4/12/2019 Dr. Josiah Yoder
Slide style: Dr. Hornick
Much Material: Dr. Schilling
Dr. Josiah Yoder

6. Nerve Speeds Speed of signal transmission along nerve fibers Speeds
SE3910
4/12/2019
Nerve Speeds
Speed of signal transmission along nerve fibers
depends on diameter of fiber & presence of myelin
large fibers have more surface area for signals
Speeds
small, unmyelinated fibers = m/sec
small, myelinated fibers = m/sec
large, myelinated fibers = up to 120 m/sec
Functions
slow signals supply the stomach & dilate pupil
fast signals supply skeletal muscles & transport sensory signals for vision & balance
Dr. Josiah Yoder

7. System Diagram Delays Distance from stick to eyes
CS2852
4/12/2019
System Diagram
Delays
Distance from stick to eyes
Speed of light = 299 792 458 m / s (google)
Neuron distance between eyes and brain stem
.1 metre
Neuron distance between brain and hands
1 metre
Time for hands to close
Hands can move up to 100 mph (44 metres per second)
Delay between muscle receiving stimulus and contraction
30-100ms, mean 55.5ms (concentric)
Rest of time will be latency in the brain
SE Dr. Josiah Yoder
Slide style: Dr. Hornick
Much Material: Dr. Schilling
Dr. Yoder

8. SE3910
4/12/2019
Exercise:
Compute the response time of the brain by subtracting all the remaining latency components from the measured latency of the stick capture.
SE-2811
Dr.Yoder
Dr. Josiah Yoder

9. Brain Speeds
Visual processing may be complete ms before subjects manually react
Frame rates of 18fps can be distinguished from smooth motion
1/(18 frames/second) = 56 ms
Much shorter strobe flashes can be detected
SE-2811
Dr.Yoder

10. SE3910
4/12/2019
Mars Reaction Time
What is the round-trip latency for sending a signal to Mars and back when it is closest to earth? (56 million miles)
What is the round-trip latency for sending a signal to Mars and back when it is farthest from earth? (401 million miles)
For spacecraft the journey takes about 250 days
What speed in MPH?
SE-2811
Dr.Yoder
Dr. Josiah Yoder

11. Slide design: Dr. Mark L. Hornick
References
EB: Derek Malloy, Exploring Beaglebone, Wiley, 2015
SE-2811
Slide design: Dr. Mark L. Hornick
Content: Dr. Hornick
Errors: Dr. Yoder